Photoelectrophoretic imaging transfer method

ABSTRACT

An electrophoretic imaging system is described in which a particulate image is transferred to a receiving sheet having a water tackifiable surface. The surface is moistened, pressed against the image and dried. In a preferred embodiment, the water tackifiable material is converted to a water insoluble form by heat after transfer of the image.

United States Patent 1191 Carreira Feb. 12, 1974 PHOTOELECTROPHORETICIMAGING 3,275,436 9/1966 Mayer 96/1 TRANSFER METHOD 2,955,035 10/1960Walkup et a1. 96/1 2,297,691 10 1942 Carlson 96/1 Inventor: LeonardCarreira, Penfield, 3,003,404 10 1961 Metcalfe et a1... 95/17 N.Y.3,192,043 6/1965 Metcalfe 1 96/1 3,355,288 11/1967 Matkan 96/1 [73]Asslgree Xerox Cowman, Rochester, 3,493,412 2 1970 Johnston et a1 117175 [22] Filed: Feb. 18, 1970 [21] A l. NQ 12,366 Primary ExaminerNormanG. Torchin Related U.S. Application Data U.S. Cl 96/l.4, 96/1 PE,96/1.2,

96/1.3, 204/181 PE lnt. Cl. G03g 13/00, G03g 13/14 Field of Search 96/1,1.4; 117/l7.5, 37

References Cited UNITED STATES PATENTS 5/1968 Tulogen ct a]: 204/181Assistant ExaminerJohn R. Miller Attorney, Agent, or Firm-James .I.Ralabate; David C. Petre; Richard A. Tomlin 5 7 ABSTRACT Anelectrophoretic imaging system is described in which a particulate imageis transferred to a receiving sheet having a water tackifiable surface.The surface is moistened, pressed against the image and dried. In apreferred embodiment, the water tackifiable material is converted to awater insoluble form by heat after transfer of the image.

6 Claims, 2 Drawing Figures PAIENIEDFEB I 2 I914 SHEET 1 BF 2 IN VENTORATTORNEY PATENIEU FEB I 2 I974 sum 2 0F 2 PHOTOELECTROPHORETIC IMAGINGTRANSFER METHOD BACKGROUND OF THE INVENTION which utilizes electricallyphotosensitive particles. This process is described in detail andclaimed in U. S. Pat. Nos. 3,384,565 and 3,384,566 issued May 21, 1968to H. E. Clark and V. Tulagin et al. respectively. In such an imagingsystem, variously colored light-absorbing particles are suspended in anonconductive liquid carrier. The suspension is placed betweenelectrodes, subjected to a potential difference and exposed to an image.As these steps are completed, selective particle migration takes placein image configuration, providing a visible image at one or both of theelectrodes. An essential component of the system is the suspendedparticles which must be electrically photosensitive and which apparentlyundergo a net change in charge polarity upon exposure to activatingelectromagnetic radiation, through interaction with one of theelectrodes. In a monochromatic system, particles of a single color maybe used, producing a single colored image equivalent to conventionalblack-and-white photography. In a polychromatic system, the images areproduced in natural color because mixtures of particles of two or moredifferent colors which are each sensitive only to light of a specificwavelength or narrow range of wavelengths are used. Particles used inthis system must have both. intense and pure colors and be highlyphotosensitive.

After the exposure and particle migration steps are completed, theelectrodes are separated and the carrier liquid is allowed to evaporate.This leaves images on one or both of the electrodes made up ofselectively deposited particles. The carrier liquid may contain a smallproportion of a wax or other binder which would serve to bind theparticles together in the images. However, if more than a very smallamount of binder material is used, undesirable interference with theimaging process takes place. Thus, the images are at this time in afragile and easily damaged condition. It has been suggested that atransparent sheet be laminated over the images, or a transparent binderresin be sprayed over the images to form a protective coating. While,when carefully done, these techniques will protect the image, the imageis often damaged during the application of the protective material.These protective techniques are not suitable for a mechanized system.Also, when it is desired to transfer the image from the electrodematerial to a receiving sheet, the dangers of smudging or otherwisedamaging an unfixed image is very great. Thus, there is a continuingneed for a better system for fixing the particulate image formed on theelectrode surface and/or for permitting transfer of said image to areceiving sheet.

A method of transferring and fixing formed electrophoretic images fromthe imaging electrode using thermo-adhesive coated sheets has recentlybeen developed. This process is disclosed and claimed in copendingapplication Ser. No. 459,860, filed June 28, 1965. For this process, atransfer sheet is prepared by coating onto the surface of a sheet, suchas paper, a layer comprising a thermosolvent dispersed in a binder. Thethermosolvent has the characteristics of being a solid at ordinarytemperatures but melting slightly above ordinary temperatures. Whenmelted, this thermosolvent dissolves the binder resin making the coatingsurface very tacky. In electrophoretic imaging, after the image has beenformed on the injecting electrode, the thermo-adhesive coated sheet isheated above the melting temperature of the thermosolvent and the sheetis pressed against the particulate image. The sheet is then cooledleaving a fixed image embedded in the surface of the thermo-adhesivelayer. This system is capable of transferring substantially all of theparticles from the electrode surface and of giving good abrasionresistance after cooling. However, this system requires specially coatedsheets and adds the need for the heating step before transfer.

Electrophoretic methods for transferring images formed on the injectingelectrode to a receiving sheet are described and claimed in copendingapplications Ser. Nos. 542,050, filed Apr. 12, 1966 now U.S. Pat. No.3,565,614 and Ser. No. 542,051, filed Apr. 12, 1966, now abandoned.Here, transfer is accomplished by placing the receiving sheet over theformed image, subjecting the formed image to a potential applied betweenthe injecting electrode and the receiving sheet while actinicelectromagnetic radiation is directed against the formed image. When thetransfer sheet is stripped away, substantially all of the imageparticles go with it. The transfer sheet may have a pressure sensitiveadhesive on the surface thereof to aid in complete transfer. This is asimple and effective transfer method. However, the image on thereceiving sheet is not fixed and is subject to smudging or other damage.

SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto provide a method of fixing a particulate electrophoretic image whichovercomes the above-noted disadvantages.

It is another object of this invention to provide a method oftransferring an electrophoretic image to a receiving sheet and fixingthe image thereto.

It is still another object of this invention to provide a method ofprotecting an electrophoretic image from damage.

It is still another object of this invention to provide anelectrophoretic imaging method capable of producing imaged sheets whichmay be handled wihout damage thereto.

It is still another object of this invention to provide an inexpensiveand non-toxic system for transferring electrophoretic images toreceiving sheets and fixing the images thereto.

The foregoing objects and others are accomplished in accordance withthis invention by providing a transfer system utilizing a transfer sheetconsisting of a paperlike material having incorporated therein aningredient which is at least partially water softenable and/ortackifiable. The sheet is used in a process in which a particulateelectrophoretic image is formed, the transfer sheet is brought intocontact with the particulate image, and the particles are transferred toit, the transfer sheet and image is then contacted with moisture toglycol, dimethacrylate, can be used as a water soluble thermosettingmedium. The following structure is representative of such a water solubl e polyester:

I 0 Hate... HassocH,cH,0-0-iin LHOCm-o-CH=O is I HOH R3NH tween thefibers. Also, the water soluble or tackifiable ingredient tends toadhesively bind the particles to the paper;

These receiving sheets are exceptionally inexpensive since the addedingredient can be incorporated into the paper during the paper makingprocess. In fact, as is pointed out below, many of the sizing agents,such as ,starch and gelatin, which are normally incorporated into paperduring the paper making process are at least partially water soluble ortackifiable so that many conventional papers may be used in thisprocess. Since no coatings need to be applied to substrates, thetransfer sheets are more economical to produce than those usedpreviously. Further, since only water is necessary to soften sheets, notoxic volatile materials need to be used which may be hazardous tooperators of machines .using the process of this invention. The finalimage sheet appears to contain an image in the surface of ordinarypaper. For many copying purposes this is desirable since the finalproduct will have the appearance of a printed paper sheet.

The water softenable or tackifiable ingredient may comprise any suitablematerial. Typical water soluble materials include water soluble resinssuch as polyvinyl alcohol, sodium alginate, copolymers ofmethylvinylether and maleic anhydride; cellulosics such as methylcellulose, ethyl cellulose, hydroxy ethyl cellulose, cyano ethylcellulose; starch derivatives such as oxidized starches, enzymeconversions, dextrine conversions, amylose, amylpectin; casein; proteinssuch as gelatin, nucleo protein, poly(surcosane), sericin; otherpolysaccharides such as algenic acids, gum arabic, gum tragacanth,heparin, pectin; and mixtures thereof. If desired, the water solublematerial may also include a pigment, such as clay, titanium dioxide,calcium carbonate; a dispersing agent, a plasticizer, a wetting agent,etc.

While images fixed with the water soluble material of this inventiongive an excellent fix with good rub resistance, the degree of fix may beadversely affected by later contact with moisture. This moisturesensitivity may be overcome where the soluble material is converted toan insoluble form by the moisture and heat during fixing. Any suitablethermo-setting material may.

be used. Typical materials include mixtures of polyvinyl alcohol andcopolymers of methyl vinyl ether and maleic anhydride; unsaturated watersoluble polyesters such as the condensation product of fumaric acid,polyethylene glycol, and pentaerythritol when mixed with a water solublediacrylate; for example, tetramethylene Also, water solublethermosetting acrylic polymers which are prepared by acid/acrylate estercopolymerization crosslinked with hexakis (methoxymethyl) melamine toconvert them to a water insoluble state are represented by the followingstructure:

CHQOOHZ Crosslink Polymer Polyvinyl alcohol can be crosslinked withaldehydes, for example, crotonaldehyde. These thermosetting watersoluble materials are considered to form a preferred embodiment of thisinvention because of their outstanding resistance to moisture damageafter fixing.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of this improvedelectrophoretic imaging system will become apparent upon considerationof the following detailed disclosure of the invention, especially whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a side view of a simple exemplary system for carrying outthe process of this invention wherein the blocking electrode and thetransfer sheet are in roller configuration.

FIG. 2 shows a second embodiment of an exemplary system for carrying outthis process wherein the transfer sheet is in the fonn of a tractormounted web.

Referring now to FIG. 1, there is seen a transparent electrode generallydesignated 1 which, in this exemplary instance, is made up of a layer ofoptically transparent glass 2 overcoated with a thin opticallytransparent layer 3 of tin oxide, commercially available under the nameNESA glass'. This electrode will hereafter be referred to as theinjecting electrode." On the surface of injecting electrode 1 is coateda thin layer 4 of finely divided photosensitive particles dispersed inan insulating carrier liquid. The term photosensitive, for the purposesof this application, refers to the properties of va particle which, onceattracted to the injecting electrode, will migrate away from it underthe influence of an applied electric field when it is exposed to actinicelectromagnetic radiation. Fora detailed theoretical explanation of theapparent mechanism of operation of 3,384,565 and 384,681, now US. Pat.No. 3,384,566, the disclosures of which are incorporated herein byreference. Adjacent to the liquid suspension 4 is a second electrode 5,hereinafter called the blocking electrode" which is connected to oneside of the potential source 6 through a switch 7, the opposite side ofpotential source 6 is connected to the injecting electrode 1 so thatwhen switch 7 is closed, an electric field is applied across the liquidsuspension 4 between electrodes 1 and 5. An image projector made up oflight source 8, a transparency 9, and a lens 10 is provided to exposethe dispersion 4 to a light image of the original transparency 9 to bereproduced. Electrode 5 is made in the form of a roller having aconductive central core 11 connected to the potential source 6. The coreis' covered with a layer of blocking electrode material 12, which may beinsulating or substantially insulating, typically Baryta paper or Tedlar(a polyvinyl floride film available from E. I. du Pont de Nemours &Company). The pigment suspension is exposed to the image to bereproduced while a potential is applied. across the blocking andinjecting electrodes by closing switch 7. Roller 5 is caused to rollacross the top surface of injecting electrode 1 with switch 7 closedduring the period of image exposure. This light exposure causes exposedparticles originally attracted to injecting electrode l to migratethrough the liquid and adhere to the surface of the blocking electrode,leaving behind a particulate image on the surface of injecting electrode1 which is a duplicate of the original transparency 9. At this time, theparticulate image on the injecting electrode is very fragile and subjectto damage. Also, since the injecting electrode is itself often ratherexpensive and fragile, it is desirable to transfer the formed image to areceiving sheet and fix the image thereon. In the embodiment shown inFIG. I, there is provided a transfer roller generally designated 13 towhich the formed image may be transferred and fixed. Transfer roller 13consists of a hollow conductive core 14 surrounded by a layer ofsubstantially insulating material 15. Layer 15 includes a material whichis at least partially soluble or tackifiable in water. As is furtherdiscussed below, this material may be a conventional water-solublesizing agent incorporated into a paper sheet during conventionalpaper-making operations. Such a paper sheet is a preferred material forus as layer 15. The surface of conductive core 14 in contact with theinner surface of layer 15 is preferably perforated or screen-like sothat moisture, typically in the form of steam, may be admitted intohollow core 14 and contact layer 15 to heat and/or moisten layer 15.Means may also be provided to admit hot, dry air or to otherwise heatlayer 15 to evaporate residual moisture therefrom after transfer of animage from injecting electrode 1 to layer 15. The conductive core oftransfer roller 13 is connected through switch 16 and power supply 17 tothe injecting electrode. It should be noted that the potential appliedto the core of the transfer roller is opposite in sign to that appliedto the core of the blocking electrode. After the image has been formedon the surface of injecting electrode 1, switch 16 is closed andtransfer roller 13 is passed across the surface of injectingelectrode 1. The layer 15 is then moistened thereby softening andtackifmg layer 15. This permits the image particles to penetrate thesurface of layer 15 and be embedded therein.

If desired, transfer roller 13 may be passed across the formed imagewithout the application of a field across the image layer betweentransfer roller 13 and injecting electrode 1. Satisfactory transfer ofthe particulate image to the transfer roller surface will occur. However, it is preferred that a potential be applied to the core of thetransfer roller opposite in sign to that applied to the core of theblocking electrode to aid complete transfer of the particulate image.This results in more complete image transfer thus producing an image ofhigher density. Also, since fewer particles are left on the surface ofinjecting electrode 1, the problems of cleaning this electrode beforethe formation of subsequent images is reduced.

While it is not necessary that the image layer be illuminated during thetransfer operation, it often increases efficiency to either project theoriginal image onto the injecting electrode surface or to flood thissurface with white light. If desired, color balance of a polychromaticimage may be corrected by flooding the injecting electrode with filteredwhite light during transfer. Such color correction is more fullydescribed in copending application Ser. No. 542,050, filed Apr. 12,1966.

FIG. 2 shows a second embodiment of a system for continuously forming aphotoelectrophoretic image,

Here, however, a tractor 18 is coupled to the blocking electrode 5 toautomatically transfer and fix the positive image formed on the NESAglass surface 3;

The tractor 18 comprises a frame 19 which supports the blockingelectrode 5 and image transfer means for movement across the imagingsurface. The transfer means consists of a continuous transfer web 20 ofsubstantially insulating material, e.g., paper which contains aningredient which is at least partially soluble in water.

The web is mounted on supply roller 21 and is adapted to pass in contactwith guide rollers 22 and 23 on its way to take up roller 24. GuideRoller 22 is hollow and has a perforated or screen-like surface. Aconduit 25 is provided to introduce moist air or steam into guide roller22. Shield means is provided to prevent excess leakage of the moist airor steam. The moisture softens and tackifies web 20 to permit theparticulate image to become embedded therein. Guide roller 23 isprovided, if desired, with means to heat and thus dry web 20. Theheating means may consist, for example, of steam admitted throughconduit 26 to the interior of closed roller 23. In operation, a mixtureof photosensitive particles in a substantially insulating carrier liquidis coated onto injecting electrode 1. The photosensitive mix is exposedto an image with switch 7 closed and the tracthe web rehardens. Ofcourse, the imaged transfer roller 'would not necessarily be rolled uponitself on roller 24. Alternatively, the web could be fed to a cuttingmeans which would cut each image area from the web and feed theindividual sheets to a receiving tray. When the tractor and blockingelectrode reach the end of their travel, brush 27 cleans unwantedpigments from the surface of blocking electrode 5. The tractor is thenraised slightly and returned to the starting position without againcontacting the injecting electrode surface. Dashed line 28 schematicallyindicates the path taken by axle 29 of the blocking electrode during theimaging and return movements. As can be seen, the deviceshcematicallyrepresented is capable of continuously forming,transferring, fixing and storing photoelectrophoretic images.

Any suitable photosensitive particle or mixtures of such particles maybe used in carrying out the imaging process, regardless of whether theparticular particle selected is organic, inorganic and is made up of oneor more components in solid solution or dispersed one in the other orwhether the particles are made up of multiple layers of differentmaterials. Typical photosensitive particles include organic pigmentssuch as those listed in copending application Ser. No. 655,022 filedJuly 21,1967 now U. S. Pat. No. 3,384,488 issued May 21, 1968 to V.Tulagin and L. Carreira the disclosure of which is incorporated hereinby reference.

As stated above, any suitable particle structure may be employed.Typical particles include those which are made up of only the purephotosensitive material or a sensitized form thereof, solid solutions ordispersions of the photosensitive material in a matrix such asthermoplastic or thermosetting resins, copolymers of photosensitivepigments and organic monomers, multilayers of particles in which thephotosensitive material is included in one of the layers and where otherlayers provide light filtering action in an outer layer or a fusible orsolvent softenable core of resin or a core of liquid such as dye orother marking material or a core of one photosensitive material coatedwith an overlayer of another photosensitive material to acheivebroadened spectral response. Other photosensitive structures includesolutions, dispersion, or copolymers of one photosensitive material inanother with or without other photosensitively inert materials. Otherparticle structures which may be used but which are not required includethose described in U.S. Pat. No. 2,940,847 to Kaprelian.

Although various electrode spacings may be employed, spacings of lessthan 1 mil and extend ir1 gdo even to the point where the electrodes arepressed together as in the case of the roller electrode constitute aparticularly preferred form of the invention in that they produce betterresolution and superior color separation results than is produced withwider spacings. This improvement is believed to take place because ofthe high field strength across the suspension during imaging.

In a monochromatic system, particles of a single color, for example, aredispersed in the carrier liquid and exposed to a black-and-white image.A single color image results, corresponding to black-and-whitephotography. In a polychromatic system, the particles areselected sothat those of different colors respond to different wavelengths in thevisible spectrum corresponding to their principal absorption bands.Also, the pigments should be selected so that their spectral responsecurves do not have substantial overlap, thus allowing for colorseparation and subtractive multi-color image formation. In a typicalsubtractive multi-color system. the particle dispersion should includecyan colored particles sensitive mainly to red light, magenta particlessensitive mainly to green light and yellow particles sensitive mainly toblue light. When mixed together in a carrier liquid, these particlesproduce a black appear ing liquid. When one or more of the particles arecaused to migrate from the injecting electrode towards the blockingelectrode, they leave behind particles which produce a color equivalentto the color of the impinging light. Thus, for example, red lightexposure causes the cyan colored particles to migrate, leaving behindthe magenta and yellow particles which combine to produce red in thefinal image. In the same manner, blue and green colors are reproduced bythe removal of yellow and magenta respectively. When white lightimpinges upon the mix, all particles migrate, leaving behind the colorof the white or transparent substrate. No exposure leaves behind allpigments which combine to produce a black image. This is an idealtechnique of subtractive color imaging in that the particles are notonly each composed of a single component but, in addition, they performthe dual functions of final image colorant and photosensitive medium.

DESCRIPTION OF PREFERRED EMBODIMENTS The details and advantages of thefixing process of the present invention will be further understood uponreference to the following examples. All parts and percentages are byweight unless otherwise indicated. The following examples should beconsidered to constitute preferred embodiments of the fixing process ofthis invention.

In each of the examples below, a suspension including three differentcolored pigments is made up by dispersing the pigments in finely dividedform in an insulating carrier liquid. This mixture may be referred to astri-mix. In each case, the imaging and transfer operations are carriedout using an apparatus of the sort schematically shown in either FIG. 1or FIG. 2, with the imaging mix coated on a NESA glass substrate throughwhich exposure is made. The NESA glass surface is connected in serieswith a switch, a potential source, in the conductive center of a rollerhaving a coating of Baryta paper on its surface. The roller isapproximately 2% inches in diameter and is moved across the platesurface at about 4 centimeters per second. The plate employed is roughly3 inches square and is exposed to a light intensity of about 1,200foot-candles as measured on the uncoated NESA glass surface. In eachcase after the blocking electrode has moved across the injectingelectrode surface leaving a positive image on the injecting electrodesurface the transfer roller or tractor is then passed across to receivethe image particles. Where a roller configuration is used, the transferroller is approximately 2% inches in diameter and is moved across theplate surface at about 4 centimeters per second. Where the tractorconfiguration is used, each of the two web support rollers isapproximately 3 inches in diameter and the tractor is moved across theplate surface at about 4 centimeters per second. Provision is includedfor imposing a potential between the transfer rollers and the injectingelectrode having a sign opposite to that imposed on the blockingelectrode core during imaging. Unless otherwise indicated, the blockingelectrode roller is held at a negative potential of about 2,500 voltswith respect to the substrate.

EXAMPLE 1 A sheet of ordinary bond paper is dipped into a solution ofabout 3 weight percent arrowroot starch (available from Will ScientificCo.) dissolved in water. The paper is dried using the radiant energy ofa General Electric infrared industrial lamp. The dried paper is wrappedaround the transfer roller in an electrophoretic imaging device of thesort shown schematically in FIG. 1. A polychromatic imaging tri-mix isprepared consisting of a cyan pigment, Monolite Fast Blue GS, the alphaform of metal-free phthalocyanine, available for E. l. du Pont deNemours & Co.; a magenta pigment, Naphthol Red B, C. 1. No. 12355,1(2'-methoxy- 5 -nitro-phenylazo)-2-hydroxy-3 -nitro-3- naphthanilide,available from Collway Colors; and a yellow pigment,8,13-dioxodinaphtho-(l,2-2',3')- furan-6-carbox-p-methoxyanilide,prepared by the method described in copending application Ser. No.421,377, filed Dec. 28, 1964 now US. Pat. No. 3,448,029. About 8 partsof a mixture of finely divided pigments is dispersed in about 100 partsSohio Odorless Solvent 3440, a kerosene fraction available from theStandard Oil of Ohio. The imaging suspension is coated onto the NESAglass surface and is exposed to a conventional Kodachrome transparencywhile the blocking electrode is passed across its surface. Immmediatelythereafter the transfer roller is passed across the NESA glass surfacewith a potential applied having a sign opposite to that used duringimaging. This electrophoretic transfer step is further described incopending application 542,050, filed Apr. 12, 1966. A loosely adheringpowder image is observed on the surface of the transfer sheet,conforming to the original. After allowing residual carrier liquid toevaporate, the image bearing transfer roller is brought into contactwith a perforated metal roller having steam admitted to its interior.The steam contacts the transfer roller moistening and heating itssurface while the particles are being pressed into firm contacttherewith. The transfer sheet is then allowed to cool to roomtemperature and residual moisture is allowed to evaporate. An excellentimage, conforming to the original, well fixed and resistant to rubbingcontact is observed on the transfer sheet.

EXAMPLE 11 Th image forming transfer and fixing steps of Example l arerepeated except that in this instance the transfer sheet is ordinarynewsprint and is dipped into a 7 weight percent solution of Carbowax4000, a polyethylene glycol available from the Union Carbide ChemicalCo. This transfer sheet is dried, wrapped around the transfer roller andan image is formed and transferred thereto as in Example 1. Afterapplication of heat and moisture as in Example 1, an excellent imagecorresponding to the original with a good fix in and on the surface ofthe transfer sheet is observed.

EXAMPLE 111 An imaging suspension is prepared consisting of a cyanpigment, Cyan Blue GTNF, C. I. No. 74160, the beta form of copperphthalocyanine, available from Collway Colors; a magenta pigment,Watchung Red B,

C. I. No. 15865, l(4-methyl-5'-chloroazobenzene-2'- sulfonicacid)-2-hydroxy-3-naphthoic acid, available from E. 1. du Pont deNemours & Co. and a yellow pigment, Algol Yellow GC, C. 1. No. 67300,l,2,5,6- di(C,C'-diphenyl)-thiazole-anthraquinone, available fromGeneral Dyestuffs. About 7 parts of this mixture of finely dividedpigments is dispersed in about parts of lsopar-G, a long chain saturatedaliphatic hydrocarbon available from Humble Oil Company of New Jersey. Atransfer sheet is prepared by dipping a sheet of ordinary bond paperinto a solution of about 5 percent by weight Gantrez AN-l39, a copolymerof methyl vinyl ether and maleic anhydride, available from GeneralAniline & Film Corp. and about 5 weight percent polyvinyl alcohol, 99percent hydrolized, available from Matheson, Coleman & Bell, in water.The resulting transfer sheet is dried and wrapped on a spool in a deviceof the sort shown in FlG. 2. The imaging suspension is coated onto theNESA glass electrode and the blocking electrode is passed across itssurface while a potential is imposed across the imaging suspension andthe suspension is exposed to a polychromatic image using a conventionalKodachrome original. After allowing the residual Isopar-G to evaporate,the tractor is passed across the image on the injecting electrode. Steamis emitted into the first roller moistening and slightly heating thetransfer paper. The second roller further heats the transfer sheet to atemperature of about C. to cause the thermosetting reaction in the resinmixture which now bonds the formed image. The image produced is ofexcellent quality, well fixed to the transfer sheet. The image isresistant to abrasion, even in the presence of moisture.

Although specific components and proportions have been described in theabove examples, other materials as listed above, where suitable, may beused with similar results. In addition, other materials may be added tothe imaging suspension or transfer material to synergize, enhance, orotherwise modify their properties.

For example, the transfer material may have colorants,

plasticizers, wetting agents, etc. added thereto, if desired.

Other modifications and ramifications of the present invention willoccur to those skilled in the art upon a reading of the presentdisclosure. These are intended to be included within the scope of thisinvention.

What is claimed is:

l. A method of photoelectrophoretic imaging comprising:

a. forming a layer of a suspension of electrically photosensitiveparticles in an insulating carrier liquid on a substrate;

b. exposing said suspension to a pattern of electromagnetic radiation ofwavelengths to which at least a portion of said particles are responsivewhile substantially simultaneously subjecting said suspension to anelectrical field until a particulate image is formed on said substrate;

c. contacting said image with a transfer member having a watertackifiable surface, said tackifiable surface being converticle to awater insoluble form;

d. transferring at least a portion of said particulate image to saidwater tackifiable surface;

e. moistening said tackifiable surface until at least a portion of saidparticulate image is embedded therein; and,

1 l 12 f. converting said tackifiable surface to its water insolubleform;

soluble form. b. transferring at least a portion of said particulate 2.The method of claim 1 wherein said tackifiable image to said watertackifiable surface; surface comprises polyethylene glycol. c.moistening said tackifiable surface until at least a 3. The method ofclaim 1 wherein said tackifiable portion of said particulate image isembedded surface comprises a mixture of polyvinyl alcohol and a therein;and, copolymer of methylvinyl ether and maleic anhydride. d. convertingsaid tackifiable surface to its water insoluble form. 4. The method oftransferring and fixing a particulate 5. The method of claim 4 whereinsaid tackifiable image of electrically photosensitive particles which 0surface comprises polyethylene glycol. comprises: 6. A method of claim 4wherein said tackifiable sura. contacting said particulate image with atransfer face comprises a mixture of polyvinyl alcohol and a comemberhaving a water tackifiable surface, said polymer of methylvinyl etherand maleic anhydride. tackifiable surface being convertible to a waterin-

2. The method of claim 1 wherein said tackifiable surface comprisespolyethylene glycol.
 3. The method of claim 1 wherein said tackifiablesurface comprises a mixture of polyvinyl alcohol and a copolymer ofmethylvinyl ether and maleic anhydride.
 4. The method of transferringand fixing a particulate image of electrically photosensitive particleswhich comprises: a. contacting said particulate image with a transfermember having a water tackifiable surface, said tackifiable surfacebeing convertible to a water insoluble form; b. transferring at least aportion of said particulate image to said water tackifiable surface; c.moistening said tackifiable surface until at least a portion of saidparticulate image is embedded therein; and, d. converting saidtackifiable surface to its water insoluble form.
 5. The method of claim4 wherein said tackifiable surface comprises polyethylene glycol.
 6. Amethod of claim 4 wherein said tackifiable surface comprises a mixtureof polyvinyl alcohol and a copolymer of methylvinyl ether and maleicanhydride.